Isomerization and alkylation of normal paraffins



Patented May 17, 1949 ISOMERIZATION ALKYLATION OF NORMAL PARAFFINS LouisA. Clarke, Fishkill, N. Y.,' assignor to The 3 Texas Company,-New York,N. ,Y., a corporation of Delaware No Drawing. Application April 10,1942,

' Serial No. 438,418

Claims. 1

This invention relates to the manufacture of motor fuel hydrocarbons ofgood anti-knock and other desirable properties-and to the production ofisobutane from normal paraflin and olefin hydrocarbons. Moreparticularly, the invention relates to a process for alkylating a normalparafiin hydrocarbon with an olefin and concomitantly isomerizing thenormal parafiin hydrocarbon, utilizing a mixed catalyst containing asessential constituents substantially anhydrous liquid hydrofluoric acidand boron fluoride.

A number of catalysts have heretofore been proposed for alkylating anisoparaffin, such as isobutane, with an olefin to produce motor fuelhydrocarbons or alkylate of ,a substantially saturated isoparafflniccharacter having high antiknock value, such as sulfuric acid, HF,BF3.H2O complex, and the like. None of the above catalysts have beenfound effective for alkylating a normal paraflin with an olefin, and anynormal parafiln present in the hydrocarbon charge remains as a diluentwhich does not take part in the reaction. U. S. Patent No. 2,217,019 hasproposed the use of a catalyst consisting of boron fluoride, nickel, HFand/or water, wherein the- HF is in a minor proportion by weight withrespect to the BFa, as a catalyst for promoting the usual alkylationreaction of isobutane with a normally gaseous olefin. This is alsodescribed in Journal of the American Chemical Society, volume 57-2,September 1935, pages 1616-1621, wherein it is stated-that a normalparaflin does not take part in the reaction.

It has now been discovered that, by the use 01' a diiferent and criticalproportion range of substantlally anhydrous liquid HF were wherein theHF is maintained in excess of the weight of the BFa, a normal paramn canbe s'lkylated with an olefin to produce good yields of normally liquidsubstantially saturated hydrocarbons within the gasoline boiling rangehaving good volatility and boiling point distribution characteristicsand other desirable properties including relatively high octane. At thesame time, this catalyst functions as an'isomerization catalyst in thepresence of the alkylation reaction and a good yield of isobutane, whichcan be employed for the conventional isoparafiin alkylation operation,is obtained. This is all the more remarkable since the combined catalystof the present invention is inactive at the temperatures employed hereinto effect isomerization of normal parafiins in the absence of a smallbut effective amount of olefin and the concomitant alkylation reaction;and the constituents of the catalyst employed separately are ineffectiveat the temperatures employed herein for producing alkylation of a normalparafiin with an olefin.

An object of the present invention resides in producing good yields ofmotor fuel hydrocarbons and of isobutane from normal paraffin and olefinhydrocarbons. particularly the normally gase us hydrocarbons of thecharacter of normal butane, ethylene and propylene, which are availablein large quantities as refinery waste gases and have not found extensiveutilization in alkylation, polymerization or other processes for theproduction of more valuable normally liquid hydrocarbons of thecharacter of motor fuel and aviation gasoline.

Another object of the present invention is to produce from such normalparaflln and olefin hydrocarbons a high-grade blending stock for motorfuel or aviation gasoline, and also substantial quantities of isobutanewhich can be employed in conventional alkylation processes for the.production of increased. quantities of highgrade alkylate. Other objectsand advantages of the present invention will be apparent from thefollowing description and the appended claims.

In accordance with the present invention, a normal paraflln hydrocarbonis reacted with an olefin under alkyiating and isomerizing conditions inthe presence of a mixed catalyst consisting essentially of a majorproportion by weight .of substantially anhydrous liquid HF and a minorbut effective proportion by weight of BF3.

The catalyst may be prepared by introducing a stream of BF: into a bodyof anhydrous liquid HF maintained under pressure until the desiredquantity of BF: has been added. It has been determined that a proportionof BF: by weight which is less than the weight of the HF is critical inefiecting the alkylation and isomerization reactions of normal parafiinsof the present invention. 0n the other hand, the presence of more thantwo mol percent of BF: is essential, and a proportion range of aboutfour mol percent to twenty mol percent of BBB, quivalent to about 14-85%by weight based on the weight of the HF, or 12-46% by weight based onthe weight of the mixed catalyst, is generally employed.

Anhydrous HF is a colorless, limpid liquid having a boiling point of19.4 C. (66.9 F.) a melting point of 83 C. and a density of 0.9918 at 4C. BF; is a fuming gas having a boiling point at atmospheric pressure of-10l C., a melting point of 127 C. and a density of 2.34 as compared toair which equals one. The temperature and pressure conditions of thepresent reaction are ordinarily such that the HF is maintained liquid,while the BF; is a gas. However, a substantial quantity of BF; passesinto solution in the HF and the hydrocarbon charge of the reaction zone,so

' that the mixed catalyst comprises anhydrous liqof the catalyst may beseparately recovered upon release of pressure without substantial loss.While the preferred catalyst is substantially anhydrous, a small amountof water may be introduced with the hydrocarbon charge and picked up bythe catalyst without impairing its efficiency, so long as the watercontent does not approach an amount which will react with .the BF: toform complex and thereby reduce the available or free BE; below thecritical range specified above. For purposes of the present descriptionand claims, it is to be understood that a catalyst containing this verysmall amount of water is included in the expression substantiallyanhydrous." The catalyst of the present invention is thus distinguishedfrom that which is prepared by adding BF: to an aqueous solution of HFor which contains an appreciable amount of water forming complex withthe available BFa.

Both normally gaseous and normally liquid parafiln hydrocarbons ofstraight chain structure, such as normal butane, normal pentane, normalhexanes and other higher boiling paraffin hydrocarbons within thegasoline boiling range and up to about C1: paraihns, can be employed asthe normal paraflin constituent of the charge. Likewise, variousmixtures of these hydrocarbons, as well as mixtures of normal paraffinand isoparaflins are suitable. Normal butane is preferred since largequantities are available which are not normally required for blendingpurposes in motor fuels to impart volatility. A parafiinic naphtha, suchas a straight run naphtha, can likewise be utilized with substantialimprovement in the volatility and other characteristics of the treatedproduct. Likewise, both normally gaseous and normally liquid oleflns aresuitable. The normally gaseous oleflns, namely, ethylene, propylene andthe butylenes, are preferred; but low boiling normally liquidmono-olefins and the low boiling olefin polymers, such as selectivepolymers of the character of di-isobutylene and tri-isobutylene,cross-polymers between isobutylene and normal butylenes, non-selectiveC3-C4 olefin polymers, and the like, can be employed.

The normal parafiin is utilized in at least an equal molar ratio withrespect to the olefin,'and preferably in a substantial molar excessthereof. For example, molar ratios of normal paraffin to olefin of 1:1to 50:1 and higher are contemplated: and generally a molar ratio inexcess of 5:1 and preferably about :1 is used. By recycling emulsion ora portion of the hydrocarbon phase of the reaction products inaccordance with conventional isoparaflln-olefln alkylation practice, aneven higher ratio at the point of contact of the hydrocarbon feed withthe catalyst may he maintained.

Ordinarily, mild temperatures within the range of 0 to 150 F. and aboveare contemplated, with temperatures of about 70-130 F. being generallypreferred. The temperature employed varies with the hydrocarbon chargestocks and the ultimate or main purpose of the reaction. For example, inthe alkylation of a normal paraffin with Ca and C4 or higher olefins, atemperature of about 50-90 F. is quite suitable. In the alkylation of anormal paraffin with ethylene, a temperature range of about 70-140" F.is usually employed, and good results have been obtained at as low atemperature as about 70 F. Where isomerization of normal paraflin in thepresence of a relatively small amount of olefin constitutes the mainreaction, temperatures in the upper portion of the range, for example,70-150 F., are quite satisfactory. Suilicient pressure is utilized topreferably maintain at least the normal parafiin constituent of thehydrocarbon charge as well as the HF in liquid phase, and to keep thedesired quantity of BFs in the reaction zone. The superimposed vaporpressure of the BF: may determine the pressure maintained in thereaction zone which will usually be about -250 pounds per square inch,although this can be varied and both higher and lower pressuresemployed.

A ratio of catalyst to total hydrocarbons maintained in the reactionzone of about 0.1:1 up-to 2:1 by liquid volume may be employed, with aratio of about 1:1 by liquid volume usually preferred. A contact time ofabout 20-120 minutes may be used with about 60-90 minutes generallypreferred. The reaction is preferably carried out with eihcientagitation, as by high-speed mechanical stirrer, circulating pump ormixer, and the like, to provide intimate contact between thehydrocarbons undergoing reaction and the catalyst.

The reaction may be carried out either in batch or continuously. In atypical batch procedure, a steel reaction bomb equipped with amechanically-driven stirrer has been employed. The reactor was chargedwith the required amount of anhydrous liquid HF and the liquefied normalparafiin. BF; was then introduced as a gas and the stirring mechanismstarted. The olefin was then charged at a regular rate over the requiredtime interval, usually about sixty minutes, and then the stirring wascontinued an additional thirty minutes. The contents of the reactor werepassed through a caustic scrubber to remove the HF, and then into astabilizer where the bulk of the gases were fractionated off andcollected. The stabilized alkylate was fractionated to note thehydrocarbon boiling range distribution, and generally a 311 F. end pointfraction of debutanized alkylate was collected and tested to obtainoctane and other pertinent data. The oflgases were generally analyzed bylow temperature fractional distillation.

The following are results of typical batch runs carried out in the abovedescribed manner with normal butane as the paraflin constituent of thecharge and with ethylene, propylene and isobutylene as the olefinconstituent:

Table I Run No. l 2 3 4 6 Catalyst:

HF Wt. in g 245 2%) 210 215 m5 BF| Wt. in g 60 50 70 50 65 HO Charge:

520 620 520 500 140 104 104 104 Operation:

Temp., "F -l 100 80 30 74 Olcfln addition time, min 55 55 60 55 143Additional stirring time, min... 30 30 30 30 30 Stabilized Alkylate:

Volume cc... 465 355 230 294 300 Wt. in g 300 2&0 185 190 Wt. (per centyield of debutani1e alkylate based on olefin charged 209 145 110 177 C.F. R. M. Mime 79.8 79.6 Oilgas, Wt. in g 300 370 450 420 Per cent lessthan C4 9.1 22.1 1.0 0.4 Per cent l-Ca 66. 6 44.0 30. 8 42. 6 Per cent11-04 22. 7 32.0 66.8 54.9 Per cent greater than C 1.7 1.9 1.4 2.1 Percent lsobutane formed based on olefin- 171 121 n-Butane. I Ethylene.Propylene. Isobutyleue.

The stabilized alkylate obtained in each of the above runs consistedlargely of pentanes and hexanes with considerable isopentane. Theresults show that alkylation is accompanied by fragmentation reactions,resulting in the formation of large percentages of isopentane andhexanes regardless of the olefin charged. At least about 95% of thestabilized total alkylate boiled below 300 F. in all instances, thisproduct having a bromine number of less than 1 showing substantialsaturation. As representative of the character and boiling pointdistribution of the alkylate produced, the following is an analysis ofthe alkylate obtained in run No. 4:

Pentanes, 37% by volume of which 25% on the volume of the total alkylatewas isopentane Hexanes, 27%

Heptanes. 13%

Octanes, 13%

Above octanes,

In all of the runs, with the exception of No. 3, it will be noted thatthe ofigas contained more than 40% by weight of isobutane; and in runNo. 1, with ethylene as the olefin constituent, the isobutane content ofthe oflgas was 66.5% equivalent to 171% on the basis of the olefincharged. Run No. 3 indicates that the temperature of 30 F. employed wastoo low for the isomerization reaction to secure high yields ofisobutane, although a fair yield of.alkylate resulted. Runs Nos. 3, 4and 5 give a comparison of operations with normal butane and isobutyleneat temperatures of 30 F., 74 F. and 115 F. respectively, and showimproved results at the higher temperatures.

The following series of batch runs indicate the eifect of the ratio ofHF to BF; in the mixed catalyst. These runs were all carried out inthebatch reactor described above with a normal butane to isobutylenemolar ratio of 5:1 and a reactor temperature of 7075 F.t

Run No. 1 shows that HF alone does not promote the alkylation of normalbutane with isobutylene. Runs Nos. 2 and 3 show that the minimumefiective concentration of BF; lies between about two mol percent andfour mol percent, beneath which neither alkylation to any appreciableextent nor isomerization takes place. The above runs show that the bestyield Jf liquid alkylate was secured with about 4-14 mol percentconcentration of BF: in the catalyst, while the maximum yield ofisobutane was obtained with about 6-19 mol percent concentration of BFa.There was a sharp decline in both the alkylation and isomerizationreactions between a BF: concentration of 19 and 30 mol percent.

Where isomerization or the production of isobutane is the primarypurpose of the reaction, only a small proportion of olefin on the basisof the normal paraffin charge is used with the HF-BFs catalyst. Thefollowing series of runs 6 were made employing normal butane and theolefin polymer di-isobutylene with HF-BFa in mol ratio of 13:1:

The above runs indicate that the highest conversion of normal butane toisobutane is secured with a molar ratio of normal butane to olefin ofabout 10:1 to 20:1, although substantial yields of isobutane are securedat ratios as high as 43:1. However, it has been found that the HF-BF:catalyst is not effective in isomerizing or producing isobutane fromeither normal butane or normal pentane in the absence of olefin. About1-2% of olefin based on the normal parafii'n charge appears to be aboutthe minimum which will produce efiective reaction. This is contrary toprevious practice in the isomerization art, where freedom from olefin inthe normal paraffin charge was considered a desideratum to avoidcatalyst deterioration and provide other advantages. Moreover, it willbe noted that the isomerization or production of isobutane occurs inhighly effective amount at comparatively low temperatures of the orderof about 70-150 F. under the conditions specified with the HF-BF;catalyst, whereas prior practices in the isomerization art generallyutilized temperatures of the order of 200 F. and above to secureeffective conversion.

As illustrating the effectiveness of the catalyst of this invention onother normal paraflins, the following three runs on normal pentane,normal heptane and a North Texas straight-run naphtha are listed:

Table IV naraflin charge 0 efln charge E Paraffin/olefin ratio, wTemperature, F"..- Contact time min Wt. per cent Yield liquid alkylatebased on total HG charge n-parafiin Yield oi oi! total B ne Yield 3?charge Wt. per cent based on isobutane, Wt. per cent based on olefincharged--. n-pfl. c

Composition of oflgas, Wt. per cent: per cent less than 04 per centisobutaneper cent n-butane per cent greater than 04 U cm 00 1 n-Pentane.

n-He time.

Next Texas SR Naphtha Boiling range 96-348 F., Original CFRM octane 63 24 isobutylene.

In each of these runs, it will be noted that the oflgas consisted ofmore than 70% by weight of isobutane, and ran as high as about in therun on normal heptane. In the normal pentane run, thealkylate containeda large percentage of isopentane, the balance being mainly hexanes,heptanes and octanes, with the major proportion boiling below the octanerange and providing a similar high volatility for blending stock asobtained in the normal butane runs. In the case of normal heptane, themajor proportion was converted to both lower and higher boilinghydrocarbons with a resultant C.,F. R. M. octane crease from to 72 forthe converted alkylate, End a substantial proportion agaln'bolling inthe lower range providing high volatility. In the case of the straightrun naphtha, the boiling range distribution of the alkylate wasadvantageously lowered with the concomitant production of a substantialamount of isobutane.

A series of continuous runs was also made in a rotary copper-linedreactor fitted with a steel shaft and impeller driven 'by an electricmotor at about 1750 R. P. M. In starting up a continuous run, therequired amount of anhydrous liquid HF was charged to the reactor, andthen the system was filled with normal paraflin, such as normal butane,and gaseous BF: then added until the pressure in the system reachedabout 200 pounds per square inch. Then a mixture of the normal paramnand olefin was added continuously while the contents of the reactor wereagi= tated. The reacted mix overflowed at a corresponding rate to a longinclined settler where most of the HF and probably some of the BF:separated from the hydrocarbon phase and was continuously recycled tothe reactor. The hydrocarbon phase containing some dissolved HF and asubstantial amount of the BF: passed through a control valve to acaustic scrubber, and thence to the product receivers and stabilizers,where the oflfgases and BF: were removed from the stabilized al ylate.This alkylate was then distilled to separate into the desired fractions,such as a 311 F. end point fraction and any higher boiling residue. 7

In an alternative procedure, BF: was added continuously with thehydrocarbon charge to provide a portion of the required amount of BF: in

the reaction zone and to make up for that which was removed with thereacted mix. In other runs, the parafiln charge was saturated with bothHF and BF: at room temperature and about 150 pounds per square inch. Ineither case, the hydrocarbon charge was divided into two parts, one partbeing a mixture of normal butane with the olefin in the desired molarratio of about :1 to :1, and the second part being the normal parafflnor normal butane saturated with HF and/or Blb. These two streams werecharged continuously into the reactor which had been previously filledwith catalyst and normal paramn as described above, so that both HF andBF: were continuously replenished to make up for losses.

The following are typical results of two continuous runs with normalbutane and isobutylene, showing the etlect of varying the molar ratio ofnormal butane to isobutylene from 5:1 to 10:1.

Table V N-butane/isobutylene mol ratio 5 10 Temperature "F. 70 '70Contact time, mm 6d 60 Yield stabilized alkylate, weight percent onolefin (aver.) 105 151 Vol. percent 311 F. E. P 70.4 93.1 Bromine No. 11 Octane No. C. F. R. M. clear 81.3 80.2 Octane No. C. F. R. M. +3 cc.

TEL/gal 95.0 Yield of isobutane, mol per cent on olefin, aver 37.2 190Pounds of alkylate per pound of catalyst, approx 2.5 1 Pounds ofisobutane per pound of catalyst. approx. 5

The above runs were carried out with continuous recirculation oicatalyst to obtain a measure of catalyst life. During the course of theruns, it was noticed that the catalyst tends to form a small amount ofhydrocarbon complex; but this is quite small in comparison to the amountfor-med with aluminum chloride, for example. The emciency of thecatalyst was eventually lowered; and when the yield of alkylate and/orisobutane has dropped to a predetermined point. as determined by directmeasurement or by extrapolation of the curve for the run, the latter wasterminated. It will be noted from the above that a 10:1 molar ratio ornormal butane to isobutylene is superior to a lower molar ratio from thestandpoint of yield of total stabilized of the oleflns, ethylene,propylene and isobutylene, in this process:

Table VI Ethyl- Propyl- Isobutylolefin used one 9118 one n-butane/oleflnmol ratio lO/l 10/1 10/1 Reaction temp., 3F 70 70 70 Contact time, min60 c0 60 Yield debutanized alkylate, wt.

percent on oleiin 277. 5 1.85. 8 151 Percent of theoretical 90. 4 18. 074. 0 Vol. percent 311 F. E. P 97.2 95. 7 93. 1 Br. No 1 1 1 Octane No.CFBM clear. 80. 8 78. 8 80. 2 Yield of isobutane:

Moi percent basis olefin. 300 250 Mo] percent basis n-butane 30 25 19Pounds alkylate per pound catalyst ed 5. 5 5. 3 4. 0 Pounds iso utaneper pound cata lyst charged 12. 0 8. 3 10. 0

Contrary to previous experience in the alkylation of an isoparaflln withan olefin in the presence of conventional catalysts such as H2804 and HFwherein the C4 oleilns have been found superior and ethylene reacts onlywith dimculty if at all, the eflectiveness of the oleflns in the presentprocess of alkylating normal parafllns is found to. vary inversely withthe molecular weight of the olefin. Thus, ethylene has been found togive the best results followed by propylene and isobutylene in thatorder.

In continuous operation, a portion of the catalyst may be continuouslywithdrawn from the system and the remaining catalyst fortified by theaddition of either HF or BF: or both, such as by being introduced withthe hydrocarbon charge. It will be also understood that the reactionproducts can be fractionated to separate any unreacted normal parafllnand the latter recycled to the system to increase the yield on the basisof the normal paraffin charge.

It has been further found that the presence of a small amount of iron,such as in the form of the metal or metal alloy, has a distinctpromoting efl'ect upon the reaction. To illustrate this efiect.continuous runs were carried out in a steel reactor in one case and in acopper-lined reactor free from exposed iron or steel surfaces in theother case. The following are data and results of these runs employingnormal butane with propylene:

It is also contemplated that salts or compounds of iron, such as ferricand ferrous fluorides, iron salts of boric and fiuoboricacids, etc., maybe employed for this purpose. Likewise, it is contemplated that othermetals above hydrogen in the electrochemical series, such as cobalt,nickel, manganese, etc., as well as alloys and compounds thereof may beused for this promotional effect.

In either batch or continuous operation, the promotional effect may beobtained by immersing a strip of cold rolled steel or other promotermetal in the reactor, which latter together with the impeller and shaftare preferably constructed of a suitable resistant metal or lining, suchas with a copper lining or of stainless steel or Monel metal, to resistcorrosion. The reactor may be fitted with a readily replaceable plug orpipe of the promoter metal, so that this is maintained in fixed positionwithin the reactor and does not interfere with the rotation of theimpeller and agitation of the contents of the reactor. It is thoughtthat the promoter metal may function as a suppressor of complexformation, giving longer catalyst life. For purposes of easydescription, it will be understood that the expression metal promoter asused in the specification and claims signifies any of the abovementioned metals, alloys or metal compounds having this promotionaleffect.

From the above description, it will be apparent that the presentinvention provides a method of alkylating a normal paraflin with anolefin with concomitant isomerization or production of isobutane,wherein a yield of alkylate of at least about 75-90% of the theoreticalon the basis of the olefin charged, and an accompanying yield ofisobutane amounting to at least about 20-30% on the basis of the normalparaffln charged, are obtained. The alkylate consists largely ofisopentane and hexanes regardless of the olefinic component of thecharge, boils almost entirely below 300 F., is substantially completelysaturated, has high lead susceptibility, and is an excellent blendingstock from the standpoint of volatility and octane blending value,particularly for leaded fuels. The present invention is thoughtparticularly valuable in providing a means for utilizing availablerefinery supplies of normal butane, ethylene, and propylene, thusproviding a one-step process for simultaneously eflecting alkylationwith the production of alkylate blending stock, and the concomitantproduction of substantial quantities of isobutane for use inconventional isoparafiin-olefin alkylation processes.

While the invention has been described above in connection with the useof an olefin for reacting with the normal paraiiin, it is to beunderstood that other alkylating agents which function similarly toolefins in the alkylation reaction can be employed. For example, alkylesters, such as alkyl fluorides, may be used. These alkyl esters may beproduced by absorbing an olefin in a suitable mineral acid, which may bethe same as the catalyst employed in the subsequent alkylation step. Theacid solution of the olefin absorption product maybe passed directly tothe alkylation zone; or the alkyl ester may be separated from theabsorption acid by the use of a a suitable solvent, such as normalbutane or other normal paraflin, and the purified ester then transferredto the alkylation reaction zone. Also, various aliphatic alcohols andethers, such as tertiary or secondary butyl alcohol, isopropyl alcohol,butyl ether, etc., may be used as the alkylating agent, although thelatter are not generally preferred for the present process since wateris liberated in t reaction requiring frequent replacement of catalyst.

Obviously many modifications and variations of the invention, ashereinbefore set forth. may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

I claim:

1. The method of treating a normally liquid parafiinic naphtha fractionto improve the volatility and other properties thereof and toconcomitantly produce isobutane, which comprises contacting the naphthain liquid phase in the presence of a minor but effective amount of anadded olefin at ordinary temperatures below about 150 F. with a mixedcatalyst consisting essentially of a major proportion by weight ofsubstantially anhydrous liquid HF and a minor but eflective proportionby weight of BF.) of the order of about 4-20 mol per cent on the basisof the mixed catalyst, and separately recovering the resultant normallyliquid hydrocarbons and the produced isobutane from the reactionproducts.

2. The method which comprises introducing a normal paraflin hydrocarbonessentially free from isobutane and an aliphatic alkylating agentselected from the group consisting of olefins, alkyl esters, alcoholsand ethers, with the normal paraflin in substantial molar excess of thealkylating agent, into a'reaction zone, and reacting the mixture thereinin the substantial absence of added isobutane and in the presence of amixed catalyst consisting essentially of a major proportion by weight ofsubstantially anhydrous liquid HF and a minor but efiective proportionof the order of 2-20 mol percent of BF3 on the basis of the mixedcatalyst under conditions including a temperature of about 0-150 F. andsufiicient pressure to maintain at least the normal paraflln in liquidphase, such that normal paraffin is alkylated by the aliphaticalkylating agent to produce substantially saturated motor fuelhydrocarbons with the concomitant production of a substantial amount ofisobutane, and separately recovering the motor fuel hydrocarbons and theisobutane from the reaction prodnets.

3. The method according to claim 2, wherein the normal paramn is normalbutane, and the aliphatic alkylating agent is a normally gaseous olefin.

4. The method of manufacturing substantially saturated hydrocarbonsboiling within the gasoline range which comprises introducingessentially a low boiling normal paraflln and an olefin, with the normalparaffin in substantial molar excess of the olefin, into a reactionzone, and reacting the mixture therein in the substantial absence thereaction products said produced normally liquid hydrocarbons andunconverted normal paraflln substantially free from isoparamn ofcorresponding molecular weight, and recycling recovered unconvertednormal paraflin substantially free from isoparailin of correspondingmolecular weight to said reaction zone.

5. The method according to claim 4, wherein the normal paraflin isnormal butane, and the olefin is a normally gaseous olefin.

6. The method of producing isobutane which comprises introducing anormal parafiin essentially free from isobutane together with a minorbut effective amount of an olefin, providing a molar ratio of normalparaflin to olefin in excess of :1, into a reaction zone, and reactingthe same therein in the presence of a mixed catalyst consistingessentially of a major proportion by weight of substantially anhydrousliquid HF and a minor but eflective proportion of the order of about6-20 mol per cent of BF: on the. basis of the mixed catalyst underconditions including a temperature of about 70-150 F. and sufllcient 1pressure to maintain at least the normal parafiln in liquid phase, suchthat a substantial amount of isobutane is produced in the resultingreaction, and recovering the isobutane from the reaction products.

7. The method according to claim 6, wherein the normal paraflin isnormal butane, and the olefin is a normally gaseous olefin.

8. The method of isomerizing a normal paraiiin hydrocarbon whichcomprises introducing a normal parafiin hydrocarbon substantially freefrom isoparafiln of corresponding molecular weight and a small buteiiective amount of an olefin, providing a normal paraiiin to olefinmolar ratio in excess of about 10:1, and reacting the mixture therein inthe presence of a mixed catalyst consisting essentially of a ma] orproportion by weight of substantially anhydrous liquid HF and a minorbut effective proportion of the order of 6-20 mol per cent of BF: on thebasis of the mixed catalyst under conditions including a temperature ofabout 70-150 F. and suiiicient pressure to maintain at least the normalparaflln in liquid phase, such that a substantial amount of isoparaflinof corresponding molecular weight is produced in the reaction, andrecovering said isoparaffin from the reaction products.

9. A method of making substantially saturated branched-chainhydrocarbons which comprises charging a normal paramn hydrocarbon to areaction zone, adding a minor mol proportion, based on the normalparaifin, of an olefin hydrocarbon to the reaction zone, reacting thehydrocarbons in the presence of a catalyst comprising essentiallysubstantially anhydrous HF and a minor mol proportion based on the totalcatalyst, of BFs, under reaction conditions wherein the pressure is suchas to maintain the hydrocarbons and the HF in liquid phase, wherein thetemperature is substantially room temperature and wherein sufficienttime is given for the reaction to form substantially saturatedbranched-chain hydrocarbons.

10. 'A method of making substantially saturated branched-chainhydrocarbons which comprises charging a normal parafiln hydrocarbon to areaction zone, adding a minor mol proportion, based on the normalparaflin, of an olefin hydrocarbon to the reaction zone, reacting thehydrocarbons in the presence of a catalyst comprising essentiallysubstantially anhydrous HF and a minor mol proportion based on the totalcatalyst, of BFs, under reaction conditions wherein the pressure is suchas to maintain the hydrocarbons and the HF in liquid phase, wherein thetemperature is within the range of about 50 F. to about F. and whereinsufllcient time is given for the reaction to form substantiallysaturated branched-chain hydrocarbons.

LOUIS A. CLARKE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,240,134 Eglofi Apr. 29, 19412,283,142 Ipatiefi et al. May 12, 1942 2,285,785 Seguy June 9, 19422,296,370 Slotterbeck Sept. 22, 1942 2,307,773 Eglofl Jan. 12, 19432,315,078 Pines et al. Mar. 30, 1943 2,317,901 Frey Apr. 27, 19432,325,122 Ipatiefi et al. July 27, 1943 2,333,648 Grosse et al Nov. 9,1943 FOREIGN PATENTS Number Country Date 516,780 Great Britain Jan. 11,1940 OTHER REFERENCES Ipatieif, Catalytic Reactions, pages 618, 682,684, 686-693.

